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Catalan's trapezoids are a countable set of number trapezoids which generalize Catalan’s triangle. Catalan's trapezoid of order m = 1, 2, 3, ... is a number trapezoid whose entries (,) give the number of strings consisting of n X-s and k Y-s such that in every initial segment of the string the number of Y-s does not exceed the number of X-s by m or more. [6]
The Catalan numbers are a sequence of natural numbers that occur in various counting problems, often involving recursively defined objects. They are named after Eugène Catalan, though they were previously discovered in the 1730s by Minggatu. The n-th Catalan number can be expressed directly in terms of the central binomial coefficients by
A square matrix is called lower triangular if all the entries above the main diagonal are zero. Similarly, a square matrix is called upper triangular if all the entries below the main diagonal are zero. Because matrix equations with triangular matrices are easier to solve, they are very important in numerical analysis.
This number is given by the 5th Catalan number. It is trivial to triangulate any convex polygon in linear time into a fan triangulation, by adding diagonals from one vertex to all other non-nearest neighbor vertices. The total number of ways to triangulate a convex n-gon by non-intersecting diagonals is the (n−2)nd Catalan number, which equals
Catalan's triangle, which counts strings of matched parentheses [2] Euler's triangle, which counts permutations with a given number of ascents [3] Floyd's triangle, whose entries are all of the integers in order [4] Hosoya's triangle, based on the Fibonacci numbers [5] Lozanić's triangle, used in the mathematics of chemical compounds [6]
Matrix chain multiplication (or the matrix chain ordering problem [1]) is an optimization problem concerning the most efficient way to multiply a given sequence of matrices. The problem is not actually to perform the multiplications, but merely to decide the sequence of the matrix multiplications involved.
The number of vertices in K n+1 is the n-th Catalan number (right diagonal in the triangle). The number of facets in K n +1 (for n ≥2) is the n -th triangular number minus one (second column in the triangle), because each facet corresponds to a 2- subset of the n objects whose groupings form the Tamari lattice T n , except the 2-subset that ...
Knowing which Catalan number it is, through the mnemonic that "the n-th Catalan number counts the case of n triangles" is intended to be the frosting on the cake. I'd like to put in the count of triangles without it getting reverted.